This project builds on a previous five year study that documented the familial basis of developmental phonology disorders (NIDCDS Grant No. DC00528). The present project will further refine the phenotype for developmental phonology disorders by examining its co-morbidity and phenotypic boundaries with language disorders and reading disorders. Various patterns of transmission, heritability, recurrent risks, and gender differences will be explored for each subtype. Preschool predictors, including family history school age outcome will be examined. Subjects include probands with a documented preschool phonology disorders, probands with a reading disorder, siblings of each proband group and parents of probands. Affection status for each individual will be determined by direct testing employing the measures developed in our previous study. This test battery assesses the domains of phonology, language, reading, spelling, written language, and intelligence. Multivariate analyses will examine different profiles of skills for each subgroup. Segregation analyses, employing the computer program POINTER, will test various models of transmission of the disorder. Family history as a predictor of school-age outcome will be explored. This study will provide insight into the causal basis for the largest group of speech and language disorders observed in children, developmental phonology disorders. By identifying subtypes of phonology disorders and their developmental course, improved understanding of phonetic, phonological, prosodic and language processes will result. Preschool predictors of later reading and spelling problems will allow more accurate prognoses, diagnoses, and long term educational planning.